Final answer:
The correct expression to determine Jackie's distance from the starting line in a race is 'Distance = Jackie's position', reflecting her position value from the start point assumed to be zero.
Step-by-step explanation:
To determine how far Jackie is from the starting line as she runs the race, we need to consider her position relative to the starting point. If we let the starting line be 0, her distance from the start is simply her position value. Therefore, the correct expression would be D) Distance = Jackie's position because her position itself indicates the distance from the starting line when measured in the positive direction of the racetrack.